// 实现这个项目的构建任务
const { src, dest, parallel, series, watch } = require('gulp')

const del = require('del')
const browserSync = require('browser-sync')//web浏览器调试插件
const loadPlugins = require('gulp-load-plugins')//统一插件加载
const plugins = loadPlugins()

const bs = browserSync.create()
// const sass = require('gulp-sass');
// const babel = require('gulp-babel');
// const swig = require('gulp-swig');
// const imagemin = require('gulp-imagemin');


const data = {
  menus: [
    {
      name: 'Home',
      icon: 'aperture',
      link: 'index.html'
    },
    {
      name: 'Features',
      link: 'features.html'
    },
    {
      name: 'About',
      link: 'about.html'
    },
    {
      name: 'Contact',
      link: '#',
      children: [
        {
          name: 'Twitter',
          link: 'https://twitter.com/w_zce'
        },
        {
          name: 'About',
          link: 'https://weibo.com/zceme'
        },
        {
          name: 'divider'
        },
        {
          name: 'About',
          link: 'https://github.com/zce'
        }
      ]
    }
  ],
  pkg: require('./package.json'),
  date: new Date()
}

const clean = () => {//删除特定目录文件
  return del(['dist', 'temp'])
}

const style = () => {//样式文件翻译构建
  return src('src/assets/styles/*.scss', { base: 'src' })
    .pipe(plugins.sass({ outputStyle: 'expanded' }))
    .pipe(dest('temp')) 
    .pipe(bs.reload({ stream: true })) ////以流的方式同步到浏览器显示，不需要刷新
}

const script = () => {//js文件babel转译
  return src('src/assets/scripts/*.js', { base: 'src' })
    .pipe(plugins.babel({ presets: ['@babel/preset-env'] }))
    .pipe(dest('temp'))
    .pipe(bs.reload({ stream: true }))
}

const page = () => {//处理html模板文件，注入数据
  return src('src/*.html', { base: 'src' })
    .pipe(plugins.swig({ data, defaults: { cache: false } })) // 防止模板缓存导致页面不能及时更新
    .pipe(dest('temp'))
    .pipe(bs.reload({ stream: true }))
}

const image = () => {//图片处理，压缩
  return src('src/assets/images/**', { base: 'src' })
    .pipe(plugins.imagemin())
    .pipe(dest('dist'))
}

const font = () => {//字体处理，图片压缩
  return src('src/assets/fonts/**', { base: 'src' })
    .pipe(plugins.imagemin())
    .pipe(dest('dist'))
}

const extra = () => {//提取文件
  return src('public/**', { base: 'public' })
    .pipe(dest('dist'))
}

const serve = () => {//热启动服务
  watch('src/assets/styles/*.scss', style)
  watch('src/assets/scripts/*.js', script)
  watch('src/*.html', page)
  watch([
    'src/assets/images/**',
    'src/assets/fonts/**',
    'public/**'
  ], bs.reload)

  bs.init({
    notify: false,
    port: 2080,
    // open: false,
    // files: 'dist/**',//监听修改文件
    server: {
      baseDir: ['temp', 'src', 'public'],//只监听开发阶段会修改的目录文件
      routes: {
        '/node_modules': 'node_modules'
      }
    }
  })
}

const useref = () => {//引用依赖插件，上线打包阶段-文件压缩等操作
  return src('temp/*.html', { base: 'temp' })
    .pipe(plugins.useref({ searchPath: ['temp', '.'] }))//构建注释转换
    // html js css
    .pipe(plugins.if(/\.js$/, plugins.uglify()))
    .pipe(plugins.if(/\.css$/, plugins.cleanCss()))
    .pipe(plugins.if(/\.html$/, plugins.htmlmin({
      collapseWhitespace: true,
      minifyCSS: true,
      minifyJS: true
    })))
    .pipe(dest('dist'))
}

const compile = parallel(style, script, page)   //编译文件

// 上线之前执行的任务
const build =  series(
  clean,
  parallel(
    series(compile,useref),
    image,
    font,
    extra
  )
)

const develop = series(compile, serve) //开发态启动命令

module.exports = {
  style,
  script,
  page,
  compile,
  clean,
  image,
  font,
  extra,
  build,
  serve,
  develop
}
